open and create databases in transaction

src/database.rs

@@ -1,10 +1,9 @@
+use libc::c_uint;
 use std::ptr;
 
 use ffi;
 
 use error::{LmdbResult, lmdb_result};
-use flags::DatabaseFlags;
-use transaction::{RwTransaction, Transaction};
 
 /// A handle to an individual database in an environment.
 ///
@@ -16,57 +15,26 @@ pub struct Database {
 
 impl Database {
 
-    /// Opens a database in the provided transaction.
+    /// Opens a new database handle in the given transaction.
     ///
-    /// If `name` is `None`, then the default database will be opened, otherwise a named database
-    /// will be opened. The database handle will be private to the transaction until the transaction
-    /// is successfully committed. If the transaction is aborted the returned database handle
-    /// should no longer be used.
-    ///
-    /// ## Unsafety
-    ///
-    /// * This function (as well as `Environment::open_db`, `Environment::create_db`, and
-    /// `Database::create`) **must not** be called from multiple concurrent transactions in the same
-    /// environment. A transaction which uses this function must finish (either commit or abort)
-    /// before any other transaction may use this function.
-    pub unsafe fn open(txn: &Transaction,
-                       name: Option<&str>)
-                       -> LmdbResult<Database> {
-        let c_name = name.map(|n| n.to_c_str());
-        let name_ptr = if let Some(ref c_name) = c_name { c_name.as_ptr() } else { ptr::null() };
-        let mut dbi: ffi::MDB_dbi = 0;
-        try!(lmdb_result(ffi::mdb_dbi_open(txn.txn(), name_ptr, 0, &mut dbi)));
-        Ok(Database { dbi: dbi })
-    }
-
-    /// Opens a handle in the provided transaction, creating the database if necessary.
-    ///
-    /// If `name` is `None`, then the default database will be opened, otherwise a named database
-    /// will be opened. The database handle will be private to the transaction until the transaction
-    /// is successfully committed. If the transaction is aborted the returned database handle
-    /// should no longer be used.
-    ///
-    /// ## Unsafety
-    ///
-    /// * This function (as well as `Environment::open_db`, `Environment::create_db`, and
-    /// `Database::open`) **must not** be called from multiple concurrent transactions in the same
-    /// environment. A transaction which uses this function must finish (either commit or abort)
-    /// before any other transaction may use this function.
-    pub unsafe fn create(txn: &RwTransaction,
-                         name: Option<&str>,
-                         flags: DatabaseFlags)
-                         -> LmdbResult<Database> {
+    /// Prefer using `Environment::open_db`, `Environment::create_db`, `TransactionExt::open_db`,
+    /// or `RwTransaction::create_db`.
+    #[doc(hidden)]
+    pub unsafe fn new(txn: *mut ffi::MDB_txn,
+                      name: Option<&str>,
+                      flags: c_uint)
+                      -> LmdbResult<Database> {
         let c_name = name.map(|n| n.to_c_str());
         let name_ptr = if let Some(ref c_name) = c_name { c_name.as_ptr() } else { ptr::null() };
         let mut dbi: ffi::MDB_dbi = 0;
-        try!(lmdb_result(ffi::mdb_dbi_open(txn.txn(), name_ptr, flags.bits() | ffi::MDB_CREATE, &mut dbi)));
+        try!(lmdb_result(ffi::mdb_dbi_open(txn, name_ptr, flags, &mut dbi)));
         Ok(Database { dbi: dbi })
     }
 
     /// Returns the underlying LMDB database handle.
     ///
     /// The caller **must** ensure that the handle is not used after the lifetime of the
-    /// environment, or after the database handle has been closed.
+    /// environment, or after the database has been closed.
     pub fn dbi(&self) -> ffi::MDB_dbi {
         self.dbi
     }

src/environment.rs

@@ -53,7 +53,7 @@ impl Environment {
     pub fn open_db<'env>(&'env self, name: Option<&str>) -> LmdbResult<Database> {
         let mutex = self.dbi_open_mutex.lock();
         let txn = try!(self.begin_ro_txn());
-        let db = unsafe { try!(Database::open(&txn, name)) };
+        let db = unsafe { try!(txn.open_db(name)) };
         try!(txn.commit());
         drop(mutex);
         Ok(db)
@@ -79,7 +79,7 @@ impl Environment {
                            -> LmdbResult<Database> {
         let mutex = self.dbi_open_mutex.lock();
         let txn = try!(self.begin_rw_txn());
-        let db = unsafe { try!(Database::create(&txn, name, flags)) };
+        let db = unsafe { try!(txn.create_db(name, flags)) };
         try!(txn.commit());
         drop(mutex);
         Ok(db)

src/transaction.rs

@@ -44,6 +44,25 @@ pub trait TransactionExt<'env> : Transaction<'env> {
         // Abort should be performed in transaction destructors.
     }
 
+    /// Opens a database in the transaction.
+    ///
+    /// If `name` is `None`, then the default database will be opened, otherwise a named database
+    /// will be opened. The database handle will be private to the transaction until the transaction
+    /// is successfully committed. If the transaction is aborted the returned database handle
+    /// should no longer be used.
+    ///
+    /// Prefer using `Environment::open_db`.
+    ///
+    /// ## Unsafety
+    ///
+    /// This function (as well as `Environment::open_db`, `Environment::create_db`, and
+    /// `Database::create`) **must not** be called from multiple concurrent transactions in the same
+    /// environment. A transaction which uses this function must finish (either commit or abort)
+    /// before any other transaction may use this function.
+    unsafe fn open_db(&self, name: Option<&str>) -> LmdbResult<Database> {
+        Database::new(self.txn(), name, 0)
+    }
+
     /// Gets an item from a database.
     ///
     /// This function retrieves the data associated with the given key in the database. If the
@@ -225,6 +244,29 @@ impl <'env> RwTransaction<'env> {
         }
     }
 
+    /// Opens a database in the provided transaction, creating it if necessary.
+    ///
+    /// If `name` is `None`, then the default database will be opened, otherwise a named database
+    /// will be opened. The database handle will be private to the transaction until the transaction
+    /// is successfully committed. If the transaction is aborted the returned database handle
+    /// should no longer be used.
+    ///
+    /// Prefer using `Environment::create_db`.
+    ///
+    /// ## Unsafety
+    ///
+    /// * This function (as well as `Environment::open_db`, `Environment::create_db`, and
+    /// `Database::open`) **must not** be called from multiple concurrent transactions in the same
+    /// environment. A transaction which uses this function must finish (either commit or abort)
+    /// before any other transaction may use this function.
+    pub unsafe fn create_db(&self,
+                            name: Option<&str>,
+                            flags: DatabaseFlags)
+                            -> LmdbResult<Database> {
+        Database::new(self.txn(), name, flags.bits() | ffi::MDB_CREATE)
+    }
+
+
     /// Opens a new read-write cursor on the given database and transaction.
     pub fn open_rw_cursor<'txn>(&'txn mut self, db: Database) -> LmdbResult<RwCursor<'txn>> {
         RwCursor::new(self, db)